WO 2004/104064 discloses polyurethane dispersants of comb microstructure having an essentially linear backbone with laterally attached solvent-solubilising side chains of polyester, polyacrylic, polyether or polyolefin including mixtures of such side chains. A subsequent application WO 2008/070601 corresponding to PCT US07/086233 filed 3 Dec. 2007 and published about Jun. 12, 2008 teaches the corresponding comb microstructure polymers with tertiary and/or quaternized amine groups.